# Mean spacing between Hemoglobin molecules

1. Oct 23, 2010

### Krazer101

1. The problem statement, all variables and given/known data
Calculate the mean spacing between hemoglobin molecules inside a red blood cell?

2. Relevant equations
Diameter of red blood cell = 5 microns
3*10^8 hemoglobin molecules in each red blood cell
Volume of hemoglobin molecule = 8.71*10^-26 m

3. The attempt at a solution
I assume we take the blood cell to be a spherical model, therefore we can find the volume of the cell. I am having trouble understanding how to use this data to find spacing inside a sphere.

2. Oct 23, 2010

### Krazer101

anyone know where to start? I was thinking to use the density of the red blood cell but I am still having trouble figuring out how to eventually get to mean spacing

3. Oct 24, 2010

### Staff: Mentor

I would treat it as a simple geometry. Calculate volume available to each hemoglobin molecules, assume it sits in the center of a cube, calculate cube edge length.

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4. Oct 24, 2010

### Krazer101

So if we take the molecule in the center, then would the separation be the distance between the center of two cubes? The separation is the cube length? I am having trouble understanding how you determine cube length. Are we supposing the molecule takes up all the possible room in the cube?

5. Oct 24, 2010

### Staff: Mentor

It is the same.

Oh come on, what is the formula for cube volume?

Doesn't matter, even if it doesn't take whole volume. Space can be filled with anything - water for example.

There is a possible problem if given molecule volume is higher than the cube volume, that would mean something is wrong.

6. Oct 24, 2010

### Krazer101

Thank you, my main problem was understanding what would happen if the molecule did not completely occupy the cube or so. Thanks for explaining it to me.